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WO1996035607A1 - Clapet d'orifice de sortie de conduit d'air pour un engin nautique a moteur - Google Patents

Clapet d'orifice de sortie de conduit d'air pour un engin nautique a moteur Download PDF

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Publication number
WO1996035607A1
WO1996035607A1 PCT/AU1996/000276 AU9600276W WO9635607A1 WO 1996035607 A1 WO1996035607 A1 WO 1996035607A1 AU 9600276 W AU9600276 W AU 9600276W WO 9635607 A1 WO9635607 A1 WO 9635607A1
Authority
WO
WIPO (PCT)
Prior art keywords
craft
flap
duct
water
rudder
Prior art date
Application number
PCT/AU1996/000276
Other languages
English (en)
Inventor
Kenneth Ronald Gale
Leanne Gaye Gale
Original Assignee
Kenneth Ronald Gale
Leanne Gaye Gale
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kenneth Ronald Gale, Leanne Gaye Gale filed Critical Kenneth Ronald Gale
Priority to AU56395/96A priority Critical patent/AU5639596A/en
Publication of WO1996035607A1 publication Critical patent/WO1996035607A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/32—Other means for varying the inherent hydrodynamic characteristics of hulls
    • B63B1/34—Other means for varying the inherent hydrodynamic characteristics of hulls by reducing surface friction
    • B63B1/38—Other means for varying the inherent hydrodynamic characteristics of hulls by reducing surface friction using air bubbles or air layers gas filled volumes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T70/00—Maritime or waterways transport
    • Y02T70/10—Measures concerning design or construction of watercraft hulls

Definitions

  • the present invention relates to a flap for minimising drag acting on a craft caused by turbulence resulting from the flow of water over a duct outlet located below the waterline of the craft, as well as a method for realising the minimisation of the drag. More specifically, the invention provides a flap for a duct outlet wherein the flap is in a closed position when the craft is travelling at low speed but which moves to an open position when the speed of the craft increases.
  • the invention has application in fields such as boat and surfboard design. BACKGROUND OF THE INVENTION.
  • the provision of a duct in surfboards for the passage of air from the atmosphere to an underside of the surfboard is known.
  • the duct consists of a passageway extending at an angle from the deck of the surfboard to the opposite underside surface of the surfboard.
  • air from the atmosphere is drawn into the inlet of the duct by a venturi effect produced by the flow of water along the underside of the craft.
  • the air subsequently passes out of the outlet of the duct located in the underside surface, and flows toward the rear of the surfboard.
  • the presence of the air underneath the surfboard causes an increase in the speed of the craft.
  • a flap in combination with a craft having at least one duct for the passage of a gas to a surface of the craft located below the waterline of the craft, wherein the flap is movable between an open position and a closed position and is arranged so as to substantially prevent water impinging on a rear peripheral region of an outlet of the duct located in the surface of the craft when the craft is travelling forward through the water.
  • a method f,or minimising drag acting on a craft having at least one duct for the passage of a gas to a surface of the craft located below the waterline of the craft comprises the step of attaching a flap to the surface of the craft to substantially prevent water impinging on a rear peripheral region of an outlet of the duct located in the surface of the craft when the craft is travelling forward through the water, and wherein the flap is attached to the surface of the craft so as to be oveable between an open and a closed position.
  • craft wherever used in this specification is to be taken to mean powered or unpowered water craft such as surfboards, sailboards, boats (including yachts) and ships.
  • duct wherever used in this specification is to be taken to encompass a passageway or conduit.
  • the flap In use, the flap is in a closed position when the craft is travelling at low speed but moves to an open position when the craft's speed increases.
  • the flap is drawn open by the flow of water over the flap in combination with the flow of air out of the duct outlet.
  • the air is drawn into the duct from the atmosphere by a venturi effect produced by the flow of the water relative to the duct outlet as the craft travels forward through the water.
  • the flap may be connected to mechanical means arranged so as to cause the flap to be opened when desired by an operator on the craft.
  • the flap is pivotally connected to the craft through pivot means.
  • the flap may be pivotally connected directly to the craft by a suitable fixative such as marine glue.
  • the flap may be formed from a variety of materials such as mylar or PVC. While it is preferable that the material from which the flap is formed is flexible, substantially rigid materials may also be used.
  • the flap may be arranged so as to lie substantially flushly on the surface of the craft in which the duct outlet is located.
  • the flap may be arranged within the duct outlet itself so that an outer surface of the flap is level with the surrounding surface of the craft in which the duct outlet is located.
  • the flap may also be distanced above the duct outlet by spacer means when the surface of the craft in which the duct outlet is located is substantially flat such as the underside surface of a surfboard.
  • the flap is substantially planar in form and typically, is rectangular in shape.
  • the flap may be one of a variety of other shapes.
  • embodiments of the present invention may reduce drag acting on a craft at low speed and so allow increased acceleration of the craft. It is a further advantage that by reducing the drag acting on powered craft savings in fuel costs may be achieved.
  • Figure 1 is a bottom view of a flap arranged over the outlet of a duct extending through a surfboard.
  • Figure 2 is a cross-sectional view of the embodiment illustrated in Figure 1 taken through X-X.
  • Figure 3 is a cross-sectional view of the embodiment of figure 1 with the flap in an open position.
  • Figure 4 is a perspective view of a flap located over a plurality of duct outlets on the rudder of a boat.
  • Figures 5a and 5b illustrate the flow of water around a conventional rudder at different speeds.
  • Figure 5c illustrates the flow of water around the conventional rudder shown in Figures 5a and 5b when partially rotated during a turning manoeuvre.
  • Figures 6a and 6b show the flow of water around the rudder of Figure 4 at different speeds.
  • Figure 6c illustrates the flow of water around the rudder of Figure 4 when partially rotated during a turning manoeuvre.
  • Figure 7 is a side view of a displacement hull incorporating a plurality of ducts and having flaps over the respective duct outlets.
  • FIG. 1 illustrates a flap 1 arranged over a duct outlet 2 on the bottom surface of a surf oard 3. Flap 1 is connected to spacing means 4 in the form of an arrow- shaped member through pivot means 5.
  • pivot means 5 is a rod about which flap 1 pivots between an open and closed position while spacing means 4 is tapered so that the water flows smoothly over its surface 6.
  • Spacing means 4 is also provided with rearwardly extending wings 7 to inhibit the flow of water under sides 8 of flap 1.
  • the bottom surface of surfboard 3 is substantially flat and spacing means 4 serves to space flap 1 from surface 3 to enable flap 1 to be drawn open by water flowing over the flap when the surfboard reaches sufficient speed during a ride.
  • the rear end 11 of flap 1 is in contact with the underside surface of surfboard 3 when in the closed position thereby substantially preventing water impinging on a peripheral region 9 of duct outlet 2 and so minimising drag acting" on the surfboard as it moves through the water during a ride.
  • flap 1 in the open position, flap 1 is substantially parallel with the underside surface of surfboard 3 as indicated in Figure 3.
  • FIG. 4 shows a rudder 12 of a boat having a plurality of duct outlets 2 which are covered by flaps 1 arranged on each side 13 of rudder 12. Flaps 1 lie flushly on sides 13 and are fixed to rudder 12 at leading end regions 14 of the flaps. Curved portions 15 of rudder 12 direct the flow of air along opposite sides 13 of rudder 12 when flap 1 is in the open position. In use, air flows into duct 10 from conduit means (not shown) which is in communication with the atmosphere.
  • flaps l may be located over duct outlets 2 on the keel of a yacht or, for example, the centre board of a sailboard.
  • each flap 1 may be replaced by a plurality of flaps, one flap being provided for each respective duct outlet 2.
  • FIGs 5a to 5c Figure 5a shows water travelling along sides 13 of rudder 1 in a laminar flow.
  • turbulence indicated by the numeral 16 is produced at the rear of rudder 12 as shown in Figure 5b.
  • the turbulence is caused by a combination of the speed of the boat and the shape of the rudder. That is, after water flows over the widest portion of rudder 12 (indicated by the line P-P) it flows inwardly towards sides 13 to fill the space left by the passage of rudder 12. Accordingly, the laminar flow of the water over the rear section of rudder 12 is broken by the inflow of water which produces drag that acts on the boat by inhibiting acceleration of the craft.
  • flaps 1 are drawn open by the movement of the water over the flaps in combination with the flow of air out through duct outlets
  • Figure 6c shows the position of the respective flaps 1 when the rudder is partially rotated during a turning manoeuvre. More specifically, flap 1 on the side 13a of rudder 12 is in a closed position while the opposite flap 1 on side 13b of rudder 11 is in an open position. The water travels along side 13a of rudder 12 in a laminar flow as for the conventional rudder illustrated in Figure 5c. However, the turbulence is substantially reduced on side 13b of the rudder as the air flows out from duct outlet 2. The open flap 1 assists in reducing the turbulence by directing the air along side 13b of rudder 12 and by guiding the water around the widest portion of the rudder.
  • FIG. 7 shows a displacement hull 17 having a plurality of duct outlets 2 located in a rear region of the hull slightly forward of where the turbulence occurs with a conventional hull.
  • Each duct outlet 2 is covered by a flap 1 to avoid drag caused by water contacting rear peripheral regions 9 of the duct outlets when the craft is travelling at low speed.
  • flaps 1 are in a closed position when the craft is travelling at low speed. However, they are drawn open by the flow of the water and by the flow of air from duct outlets 2 when the speed of the craft increases. The air acts to reduce the turbulence produced at the rear of the hull by the passage of the craft as discussed above.
  • duct outlets 2 are located on hull 17 the greater the speed of the craft required to cause flaps 1 to be opened due to the pressure of the water acting on the flaps.
  • duct outlets 2 are located within a depth of 1 metre from the water line.
  • flaps 1 may be operated by mechanical means controlled by an operator on the deck of the boat.
  • duct outlets 2 in the accompanying drawings are shown as being covered by a single flap 1, embodiments of the invention may be provided wherein a duct outlet 2 is provided with a plurality of flaps 1 which co-operate with each other to substantially prevent water impinging on the rear peripheral region 9 of duct outlets 2 as the craft travels through the water.

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Cooling, Air Intake And Gas Exhaust, And Fuel Tank Arrangements In Propulsion Units (AREA)

Abstract

La présente invention concerne un clapet (1) destiné à un engin nautique à moteur comportant au moins un conduit (10) assurant le passage d'un gaz en direction d'une surface de l'engin nautique à moteur, l'orifice étant situé sous la ligne de flottaison. En l'occurrence, le clapet (1), monté sur pivot au niveau de l'orifice de sortie (2) du conduit, est mobile entre une position ouverte et une position fermée. En utilisation, le clapet (1) est en position fermée lorsque l'engin nautique à moteur avance à basse vitesse, ce qui permet sensiblement d'empêcher l'eau de pénétrer dans la zone périphérique postérieure (9) de l'orifice de sortie (2) du conduit, le clapet venant en position ouverte lorsque la vitesse de l'engin nautique à moteur augmente.
PCT/AU1996/000276 1995-05-09 1996-05-09 Clapet d'orifice de sortie de conduit d'air pour un engin nautique a moteur WO1996035607A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU56395/96A AU5639596A (en) 1995-05-09 1996-05-09 A flap for an air duct outlet for a watercraft

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPN2891A AUPN289195A0 (en) 1995-05-09 1995-05-09 A flap for a duct outlet
AUPN2891 1995-05-09

Publications (1)

Publication Number Publication Date
WO1996035607A1 true WO1996035607A1 (fr) 1996-11-14

Family

ID=3787239

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1996/000276 WO1996035607A1 (fr) 1995-05-09 1996-05-09 Clapet d'orifice de sortie de conduit d'air pour un engin nautique a moteur

Country Status (2)

Country Link
AU (1) AUPN289195A0 (fr)
WO (1) WO1996035607A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005041439A1 (de) * 2005-08-31 2007-03-15 Nikolakis, Dimitrios, Dr. Ing. Wasserfahrzeug
EP2562075A1 (fr) * 2011-08-24 2013-02-27 Zuei-Ling Lin Procédé de réduction de la résistance de gouvernail
TWI557025B (zh) * 2011-08-05 2016-11-11 林瑞麟 降低船隻方向舵（Ｒｕｄｄｅｒ）阻力之方法
WO2022071813A1 (fr) * 2020-09-30 2022-04-07 Venairjet Systems Limited Appareil et système d'introduction d'air sous une coque de bateau

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1408178A (en) * 1920-11-20 1922-02-28 Downing Virgil Sidney Boat construction
FR702733A (fr) * 1929-12-20 1931-04-15 Aéro-hydroglisseur
US3267898A (en) * 1965-06-10 1966-08-23 Carmi G Evans Amphibious vehicle
US3871318A (en) * 1971-06-16 1975-03-18 Ernest Joscelyn Clerk Antifriction device for boat hulls
FR2293359A1 (fr) * 1974-12-05 1976-07-02 Neiman Sa Expl Brevets Perfectionnements aux voiliers
WO1981001540A1 (fr) * 1979-11-26 1981-06-11 Surf Jet Corp Planche de surf motrice
JPH0656068A (ja) * 1992-08-11 1994-03-01 Mitsubishi Heavy Ind Ltd 水中翼船の舵フラップ装置

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1408178A (en) * 1920-11-20 1922-02-28 Downing Virgil Sidney Boat construction
FR702733A (fr) * 1929-12-20 1931-04-15 Aéro-hydroglisseur
US3267898A (en) * 1965-06-10 1966-08-23 Carmi G Evans Amphibious vehicle
US3871318A (en) * 1971-06-16 1975-03-18 Ernest Joscelyn Clerk Antifriction device for boat hulls
FR2293359A1 (fr) * 1974-12-05 1976-07-02 Neiman Sa Expl Brevets Perfectionnements aux voiliers
WO1981001540A1 (fr) * 1979-11-26 1981-06-11 Surf Jet Corp Planche de surf motrice
JPH0656068A (ja) * 1992-08-11 1994-03-01 Mitsubishi Heavy Ind Ltd 水中翼船の舵フラップ装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, M-1615, page 97; & JP,A,06 056 068 (MITSUBISHI HEAVY IND LTD), 1 March 1994. *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005041439A1 (de) * 2005-08-31 2007-03-15 Nikolakis, Dimitrios, Dr. Ing. Wasserfahrzeug
TWI557025B (zh) * 2011-08-05 2016-11-11 林瑞麟 降低船隻方向舵（Ｒｕｄｄｅｒ）阻力之方法
EP2562075A1 (fr) * 2011-08-24 2013-02-27 Zuei-Ling Lin Procédé de réduction de la résistance de gouvernail
WO2022071813A1 (fr) * 2020-09-30 2022-04-07 Venairjet Systems Limited Appareil et système d'introduction d'air sous une coque de bateau

Also Published As

Publication number Publication date
AUPN289195A0 (en) 1995-06-01

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